Sewing machines



March 24, 1959 K. WINZ.

SEWING MACHINES Filed March 29, 1955 they can readily be inspected.

United States O SEWING MACHINES Karl Winz, Kaiserslautern, Germany, asslgnor to Pfalf Aktiengesellschaft, German company Application March 29, 1955, Serial No. 491,711

Claims priority, application Germany March 50, 1954- 4 Claims. (Cl. 112-219) I Kaiserslautern, Germany, a

This invention relates to sewing machines. In the operation of sewing machines, and especially those having an electric drive, it is frequently necessary to carry out switching operations in electric circuits in the co-operating parts of the contacfni'aker" may be ofparticularly simple design andimay be so? arranged that In accordance with the invention there is setir e'd to the needle bar of the sewing machine a holder which carries contact pins adapted to slide over contact strips in a contact strip carrier. The contact times, contact sequences and the like may be varied by appropriate arrangement and shaping of the contact strips on the contact strip carrier. Preferably, the contact strip carrier is secured to the device for the adjustment of the thread tension, for example by means of screws.

Further features of the invention and details of the advantages thereby afforded will become apparent from the following description of one embodiment of the invention illustrated in the accompanying drawings, in which:

Figure 1 shows the open head of a sewing machine with a contact maker arrangement according to the invention,

Figure 2 is a front elevation of the contact strip carrier,

Figure 3 is a side elevation of the contact strip carrier, showing the contact pin holder partly in section,

Figure 4 shows the needle bar pin with the contact pin holder, and

Figure 5 is a wiring diagram of the electric circuit.

A needle bar 2 and a presser bar 3 are disposed together with a thread tension regulator 4 in the usual manner in the sewing machine head 1. The needle bar 2 receives its upward and downward movement from an arm shaft 5 through an arm shaft crank 6, a needle bar link crank 7, a needle bar link 8 and a needle bar pin 9 (Fig. 4). The latter grips the needle bar 2 by means of a clip 10, which may be tightened by a screw 11.

Secured to the clip 10 by means of the screw 11 is a contact pin holder 12, which supports in two sockets 13 contact pins 14 and 15, which are axially slidable in said sockets and subjected to the action of coil springs 16 (Fig. 3). A contact strip carrier 17 consisting of insulating material is provided with two threaded holes 18 (Fig. 2) and is secured by two screws 19 to the thread tension regulator 4. Two contact strips 20 and 21 (Fig. 2) are let into the contact strip carrier 17 and are provided respectively with terminal connectors 22 and 23 (Fig. 3) projecting from the contact strip carrier 17 towards the cover side of the sewing machine head 1.

2 The two contact pins 14 and 15 are interconnected electrically by means of the pin holder 12 and are conductively connected with the mass of the sewing machine, for grounding. The pins 14 and 15 make sliding contact with the strips 20 and 21 during the up and down .reciprocable movement of the needle bar 2. The pins 14 and 15 form with the strips 20 and 21 a switch. Each contact strip 20 and 21 may alternatively be connected with an electric source B, by means of a two position switch 26 (Fig. 5). The pin sliding on the contact strip that is connected to the source B will by means of that contact close the electric circuit, and the electric circuit will be interrupted when the pin owing to the needle bar movement reaches a position on the contact strip carrier 17 beyond the extent of the contact strip. In particular, in the upper needle position, the pin 14 will be out of contact with the strip 20, while the pin 15 is still in contact with the strip 21 (as shown in Fig. 5), and in the lower needle position the pin 15 will be out of contact with the strip 21 while the pin 14 is still in contact with the strip 20. Thus, when the switch 26 is interconnected to the strip 20, the circuit will be interrupted when the needle is in the upper position, but will not be interrupted when the needle is in the lower position. Conversely, when the switch 26 is interconnected to the strip 21, and thereby disconnected from the strip 20, the circuit will beinterrupted in the lower needle position but will remain uninterrupted in 'the' upper needle position.

The remaining parts of the circuit include leads 24 and 25 between the switch 26, and the terminal connectors 22 and 23 of the contact strips 20 and 21, respectively. The switch 26 is interconnected by a lead 27 with one pole of the source B, such as a battery, the other pole 29 of which is grounded.

Means for stopping the needle in either its upper or lower dead center position, may be provided, for instance as disclosed in my copending application Serial No. 446,517 that was filed on July 29, 1954.

In the illustrated embodiment the circuit to be switched is interrupted at the upper and lower dead centre positions in the movement of the needle bar, While it is closed throughout the remainder of each oscillation of the needle bar. By varying the shape and construction of the contact strips let into the insulating plate of the contact strip carrier, switching combinations may be produced in any desired variations in a number of circuits in combination with further circuit elements.

It will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specific exemplifications thereof will suggest various other modifications and applications of the same.

It is accordingly desired that in construing the breadth of the appended claims they shall not be limited to the specific exemplifications of the invention described herein.

What I claim as my invention and desire to secure by Letters Patent of the United States is:

l. A device for making and breaking an electric circuit, for use in connection with a sewing machine having a reciprocable element, said device comprising in combination a source of electric current, two movable electric contacts reciprocable with said element between opposite dead center positions, a carrier fixed relative to the movement of said contacts and including two contact strips each positioned alongside a portion of the path of one of said contacts, whereby during a portion of the movement of said contacts each will be in sliding contact with a contact strip to complete a circuit, insulating members upon said carrier adjacent each contact strip and positioned alongside the remainder of the path of the cooperating movable contact, said insulating mem- 3 bers being so disposed that one insulating member will be engaged by one movable contact in one dead center position of said element, to break a circuit between said last mentioned movable contact and a contact strip, and the other insulating element will be engaged by the other movable contact in the opposite dead center position of said element for breaking an electric circuit between said other movable contact and the cooperating contact strip, switch, means to connect either contact strip to one pole of said source, said movable contacts being grounded by the mass of the sewing machine, and said mass being connected to the other pole of said source.

2. In a sewing machine, a vertically reciprocable needle bar, an electric circuit including contact pins reciprocable with said needle bar, and a control strip carrier comprising a plate of insulating material and conductive control strips let in said plate, said control strips being fixed relative to said contact pins and each contact strip disposed alongside the path of a contact pin and having a length less than said path and, cooperating with a contact pin, to make and break said circuit.

3. A sewing machine having a reciprocable needle bar being adaptedto stop said machine when said needle bar is in at least one predetermined position, comprising an electric circuit including a fixed contact and a moving contact cooperating therewith and mounted on said needle bar, said fixed contact extending alongside a portion of the path of said moving contact, an insulator adjacent to the remainder of said path corresponding to said predetermined position of said needle bar, whereby to interrupt said contacts in said predetermined position of said needle bar.

4. An electric contact making and breaking circuit for use in sewing machines having a needle bar operable to break an electric circuit when the needle bar is in a dead center position and to complete said circuit in all other needle bar positions, comprising in combinaton a source of electric current, two, movable electric contact pins reciprocable with said needle bar, a carrier fixed relative to the movementiof said contact pins and including two contact strips each being positioned alongside the path of reciprocation-of a contact, pin, said contact strips being ofiset relative to one another so that one of said contact pins will be in sliding contact with a contact strip for a portion of its path including one dead center position and out. of contact in the other dead center position, and that the other contact pin will be out of contact with its contact strip in the. opposite dead center position of said needle bar, said contact pins being connected to one pole of said source by way of the mass of said sewing machine, said contact strips being alternately connectable to the other pole of said source, whereby either of said contact pins upon engaging the cooperating contact strip forms with said mass a closed electric circuit including said source, and whereby, when said source is connected to one of said contact strips, said circuit will be interrupted in one dead center position of said needle bar and, when said source is connected to the other contact strip, said circuit will be interrupted in the opposite deadcenterposition of said needle bar.

References Cited in the file of this patent STATES PATENTS 2,708,415 White May 17, 1955 

